The present invention relates generally to dynamic pressure or density measurement, and, more specifically, to microphones for detecting acoustic energy or sound.
A typical microphone is a transducer which converts acoustic energy into electrical energy. This is typically accomplished by allowing the acoustic energy to vibrate a diaphragm or membrane, with the vibration thereof being converted to an electrical signal indicative of the acoustic energy. However, the diaphragm inherently has mass which affects the ability of the microphone to accurately detect the original acoustic energy.
Various types of microphones are known which vary in sophistication and ability to accurately detect the acoustic energy. The microphones are evaluated by various performance criteria including frequency range and response, dynamic range, sensitivity, and polar pattern or the directional response capability of the microphone.
Of particular interest is the microphone sensitivity which is typically expressed by the output voltage of the microphone for a particular sound pressure level. High microphone sensitivity is desired for discriminating against system noise and other electrical interference.
The polar pattern, or the directional response of the microphone is another important parameter to avoid the detection of unwanted sound or sources while linking the detection capability of the microphone to a specific direction.
The diaphragms are typically made as thin and lightweight as possible to limit their adverse affect on accurately detecting acoustic energy or sound. A low mass diaphragm is desirable for obtaining a flatter frequency response, and improved microphone sensitivity. However, the diaphragm is therefore subject to large excursions in travel under a large pressure wave such as that occurring upon the pronunciation of "P" words. This causes undesirable popping response from the microphone when used for example in a public address speaker system.
Accordingly, it is desired to provide a diaphragm-less microphone for detecting acoustic energy without the typical problems associated with a diaphragm-microphone while obtaining good sensitivity, frequency range and response, and directional response, for example.